1) Field of the Invention
The present invention relates to an apparatus, such as a capsule endoscope, that acquires information about internal structure of a patient (hereinafter, “in-body information acquiring apparatus”) and a power-supply circuit.
2) Description of the Related Art
A swallowable capsule endoscope for medical treatment that can be introduced into the abdominal cavity of a patient and that collects information about internal structure of the abdominal cavity by taking pictures has been known. Japanese Patent Application Laid-open Publication No. 2002-508201 discloses a capsule endoscope in which are inbuilt an illuminating unit, which includes a light emitting diode (LED) etc.; a solid-state image sensor, which includes a charged coupled device (CCD) or a CMOS (complementary metal-oxide semiconductor); and a power-supply unit, which includes a battery cell (hereinafter, “cell”) that supplies power to the illuminating unit or the solid-state image sensor.
The capsule endoscope has to be small so that a patient can swallow it. Thus, there is a great limitation on the size of the capsule endoscope and there is much greater limitation on the size of the cell of the capsule endoscope.
Moreover, since the capsule endoscope is required to operate stably, the cell has to be capable of supplying a stable predetermined voltage.
Since it is almost impossible to reuse the capsule, it is desirable that the capsule endoscope is cheap. To suppress the cost, one approach is to use the cells that are available in the market and not go for custom-made cells. Button cells that are used in wrist watches, portable games, thermometers etc. may be used in the capsule endoscopes; however, only limited types of such cells are available in the market and to choose a cell that satisfies the requirements of size, shape, life, output level etc. for use in the capsule endoscope is a difficult task.